Aqueous medium of a water insoluble additive for mineral fiber insulating materials

ABSTRACT

Insulating materials consisting of artificial mineral fibers are impregnated with water insoluble additives, e.g. dust binders and/or water repellant finishing agents in that they are wetted with an emulsion of the water insoluble additive in an aqueous solution of a cellulose ether. Impregnation takes place easily and is effective and resistant.

This is a division of application Ser. No. 07/049,534, filed on May 14,1987 now U.S. Pat. No. 4,957,559.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to an aqueous emulsion of a water insolubleadditive for insulating materials which consist of artifical mineralfibers, and a method of producing such aqueous emulsions and their usefor impregnating (oiling) the synthetic mineral fibers. The inventionfurther relates to insulating materials consisting of synthetic mineralfibers which are impregnated by using such aqueous emulsions.

2. Discussion of the Background

In order to improve their handling properties, insulating materialswhich consist of synthetic mineral fibers are impregnated with additivessuch as, for example, dust binders, water repellants, smoothing andlubricant agents as well as other additives. Furthermore, syntheticplastics in the form of thermohardenable duromers such as, for example,phenolformaldehyde resins, are added in order to impart a certain formstability to the mineral fibers in the bonded material.

In order to achieve an even distribution of these additives throughoutthe mineral fibers which are further processed in the form of a fiberstrip, it is necessary for the additives to be incorporated at a stagein the manufacturing process at which the fibers can still beimpregnated as individual fibers, in other words before the felted fiberweb is formed. This stage in the manufacturing process is in theimmediate vicinity of the disaggregating units where, by reason of theproximity of molten glass, high temperatures, intensive radiated heatand the latent risk of fire are present.

Therefore, the additives have to fulfill a number of conditions, i.e.,they must have low inherent volatility; it must be possible to dilutethem with water; it must be possible to work them by spraying, and theymust not burn when being processed.

In current processes, these conditions are fulfilled by aqueousemulsions or dispersions of the additives which have the necessarystability and which can be diluted to the desired low workingconcentration by the addition of water. Insulating materials consistingof mineral fibers and impregnated with these additives are, however,only conditionally suitable for practical use.

The production of an aqueous emulsion of mineral oils which can be usedas a dust binding agent, silicones which can be used as water repellantsand similar water-insoluble substances is possible only by usingemulsifiers. Emulsifiers are surface-active substances of goodsolubility both in the aqueous and also in the non-aqueous phase. Withmineral oil emulsions which are described in the insulants industry as"oiling materials", outstanding values of dust bonding are achieved. Theeffect can be attributed to two causes:

1. The oiling substance consisting of mineral oil acts as a lubricantduring the relative movements of compacting fibers. Thus, friction ofglass on glass is reduced and this also reduces the risk of cracking andshattering of glass (glass fibers).

2. Despite all these precautionary measures the dust formed remainsclinging to intact fibers and cannot be thrown off into the ambient air.This effect is a consequence of the tackiness of viscous mineral oils.Therefore, impregnation with dust binders is an essential condition forthe marketability of an insulating material which consists of syntheticmineral fibers.

It has, however, been demonstrated that insulating materials impregnatedwith dust binders easily absorb water. For example, if an insulating matimpregnated with dust binders is placed on water, it rapidly swells upand sinks. Water such as, for instance, rain water sprayed onto such amat is absorbed and soaks the mat. This represents a considerabledisadvantage because insulating materials consisting of mineral fiberswhich have become wetted in use, for example by rain, have to be driedout at considerable expense and there is a latent risk of corrosion frominsulating materials which are not fully dried. Furthermore, manyemulsifiable mineral oils or other water insoluble additives can bewashed out by the action of the clinging emulsifier.

Even silicones which can be used as additives for the water repellantfinishing of insulating materials consisting of mineral fibers can as arule only be processed to produce stable aqueous emulsions by theaddition of solvents and if they have very high proportions ofemulsifier. Therefore, the hydrophobic action of the silicone is oftenweakened and sometimes even cancelled out entirely by the hydrophilicinfluence of the emulsifier, so that the addition of silicone becomespointless. Only with particular technical complications can theemulsifier--once the emulsion has been applied to mineral fibers--be soaltered that it loses its emusifying effect.

Therefore, numerous experiments have been made with a view to avoidingor circumventing the aforesaid disadvantages of processingemuslifier-containing emulsions to produce additives for use withmineral fiber-containing insulating materials. During an attempt toreduce the quantity of added emulsifier, however, the emulsion becametoo unstable so that the target, i.e. a water repellent finish, couldnot be achieved.

Furthermore, alkali or ammonium soaps of fatty or resinous acids havingbeen used as emulsifiers. Such substances can be used as effectiveemulsifiers for highly viscous mineral oils even if the quantity used isonly 5% of the mineral oil. The emulsifying effect of soaps can berendered ineffective by chemical precipitation with lime-milk, e.g. bythe simultaneous spraying of soap-containing emulsion and lime-milk.Ammonium soaps can also be destroyed by thermal decomposition as theimpregnated product passes through a continuous dryer. It is obviousthat the additional spraying of lime-milk or the additional proceduralstep of heating in a continuous dryer represent a disadvantageoustechnical and economic complication.

Furthermore, a process is known in which the highly viscous mineral oilused an additive for the insulating materials is so diluted by theaddition of an organic solvent that its viscosity becomes similar tothat of water. In this form, the mineral oil solution is worked into thesynthetic resin solution by means of static mixers and is sprayedjointly with it. The method calls for a high proportion of solvent, of25 to 40% in relation to the mineral oil used as the dust binder andincreases the hydrocarbon emission of the plant to two to three timesits original level.

SUMMARY OF THE INVENTION

Accordingly, one object of the present invention is to provide a methodof easily and effectively and as far as possible, permanently,impregnating insulating materials which consists of artificial mineralfibers with additives such as dust binders, water repellent finishingagents, and smoothing and lubricating agents.

A further object of the invention is to provide a method of impregnatingfiber insulating materials which produces insulating materials whichabsorb as little water as possible.

These and other objects of the present invention which will becomeapparent from the following specification have been achieved by thepresent method of producing an aqueous emulsion of a water insolubleadditive for artificial mineral fiber insulating materials, whichcomprises the steps of (a) preparing an aqueous solution of a celluloseether, and (b) dispersing the water insoluble additive in the aqueoussolution.

These objects are also achieved by the aqueous emulsion produced by thismethod and by the impregnated mineral fibers so produced.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

According to the method of the invention, water insoluble additives suchas, for example highly viscous mineral oils, can form emulsions in aviscous solution of water soluble cellulose ethers without the use of anemulsifier or other surfactants, while using heavy duty dispersingunits. Finely dispersed stable emulsions are formed in water which aresufficiently resistant for processing under factory conditions. Theseemulsions can be diluted with conventional agitating means (anchor,blade or bar mixers) to application concentrations with 1% or lessactive principle content and are miscible with conventional syntheticresin binders and offer appropriate resistance.

Preferred cellulose ethers are alkyl, aralkyl, hydroxyalkyl andcarboxyalkyl ethers of cellulose which have no or only weakly markedproperties which reduce surface tension. The use of cellulose ethers asemulsifying aids is known, and they act as a protective colloid in orderto counteract the coalescence of formed emulsions. They enclose theformed droplets of oil in water without penetrating directly into theinner oil phase like the emulsifiers, i.e. without dissolving in it. Byvirtue of their insolubility in oil, the cellulose ethers of the outerphase are added to the water in which they are readily soluble andmaintain the once-formed emulsion droplets in suspension. However, itwas not known that cellulose ethers make it possible to produce aqueousemulsions of additives for insulating materials which consist ofartificial mineral fibers and have the effect of permanently coating theadditives on the artificial mineral fibers.

Of the cellulose ethers which can be used according to the invention,hydroxyethyl cellulose, methylhydroxyethyl cellulose andsodium-carboxymethyl cellulose are particularly preferred, because theyare non-ionic and are compatible with phenolic resins. They arepreferred used in quantities of 0.1 to 2.5%, particularly 0.2 to 1.0% inrelation to the water insoluble additive. Most often used as a waterinsoluble additive is a dust binder and/or water repellent finishingagent which are known in the field and are quite conventional, thepreferred dust binder being a mineral oil while the preferred waterrepellant finishing agent is a silicone.

Heavy duty dispersing units which may be used in the method according tothe invention are those which mechanically achieve a fine dispersion ofthe water insoluble additive, e.g. the oil or silicone, by applyingsufficiently high shearing forces. Such heavy duty dispersion units are,for instance, the units marketed under the trade names Ultra-Turrax® orDispax® by Janke and Kunkel.

Other features of the invention will become apparent in the course ofthe following descriptions of exemplary embodiments which are given forillustration of the invention are not intended to be limiting thereof.

EXAMPLES EXAMPLE 1 Production of an Oil Emulsion of a Water RepellantFinishing Agent by the Batch Process

The following components were placed in a 120-liter mixing container:

(a) 200 kg of a 0.75% aqueous solution of hydroxyethyl cellulose (HEC)under the designation Tylose H 100,000® of Hoechst AG,

(b) 300 kg production oil, specifically heated steam cylinder oil ZB DIN51 510 (a mineral oil),

(c) 500 kg completely deionized water.

Heated to 50° C., the HEC solution and the production oil (mineral oil)are intensively blended for 10 to 15 minutes with an Ultra-Turrax® heavyduty dispersion unit made by Janke and Kunkel which, by applying highshearing forces, achieves a sufficiently fine dispersion of the oil bypurely mechanical means, until a mixture results which is entirelyhomogeneous in color. Afterwards, the completely deionized water at 20°to 25° C. is add to the mixture, accompanied by agitation. The additionis begun slowly and then at an increased rate.

1000 kg of a 30% basic emulsion are obtained which can be furtherprocessed to any desired concentration for use.

EXAMPLE 2 Production of an Oil Emulsion of a Water Repellant FinishingAgent by the Continuous Method

The production components for a 30% basic emulsion are:

(a) 200 kg of a 1% aqueous solution of sodium carboxymethyl celluloseunder the designation CBR 10,000-np® of Hoechst AG,

(b) 300 kg mineral oil, Fiona ZB grade, produced by Shell AG,

(c) 500 kg completely deionized water.

From two storage containers, the mineral oil heated to 50° C. and the 1%aqueous solution of sodium carboxymethyl cellulose are drawn by means oftwo piston dispensing pumps and fed to a continuously operatingdisperser of the Dispax Reactor type (Janke and Kunkel), by threeserially connected rotor stator blades in a volume ratio of mineral oilto sodium carboxymethyl cellulose solution of 3:2. Upon a single passagethrough the plant, the two components are intensively blended with aresidence time of approximately 2 sec.

Afterwards, this mixture is conducted into a second Dispax Unit of thesame construction where, by the addition of five parts of the fullydeionized water, the emulsion is diluted to 30%.

By the addition of further quantities of water in a static mixer, theresultant emulsion can be diluted to the desired usage concentration of2 to 8%.

It is also possible according to the method of the invention to dispersesilicone oils, reactive silicone oils and mixtures of these substanceswith mineral oil, as the following Examples demonstrate:

EXAMPLE 3 Production of an Oil Emulsion of a Water Repellant FinishingAgent by the Batch Method

The production components for a 30% basic emulsion are:

(a) 150 kg of a 1% aqueous solution of methyl hydroxyethyl cellulose(CMC), specifically Tylose C 10,000® of Hoechst AG,

(b) 240 kg production oil (mineral oil) specifically heated steamcylinder oil ZB DIN 51 510 of Shell AG under the designation ShellProduction Oil 0303,

(c) 60 kg of silicone oil of type "DC 200/100 cSt., fluid" ofDow-Corning,

(d) 550 kg fully deionized water.

The procedure is the same as in Example 1, mineral oil and silicone oilbeing pre-mixed prior to addition of the solution of sodiumcarboxymethyl cellulose.

EXAMPLE 4 Production of a Mixed Water Repellant Finishing Agent in aBatch Process

The production components for a 30% basic emulsion are:

(a) 200 kg of a 0.75% aqueous solution of hydroxyethyl cellulose,specifically Tylose A 1000® of Heochst AG,

(b) 240 kg production oil, specifically super heated steam cylinder oilZB DIN 51 510 production oil No. 6 of Kompressol,

(c) 60 kg silicone oil with reactive Si-H groups, DC 1107 Fluid® of DowCorning,

(d) 550 kg fully deionized water.

The procedure is the same as in Example 1. The mineral oil is pre-mixedwith the silicone oil before the hydroxyethyl cellulose solution isadded.

EXAMPLE 5 Production of a Silicone Oil Emulsion of a Water RepellantFinishing Agent by the Continuous or Batch Process

The production components for a 30% basic emulsion are:

(a) 300 kg of a 0.75% aqueous solution of hydroxyethyl cellulose,specifically Tylose A 1000® of Hoechst AG,

(b) 300 kg silicone oil, Tego CK 500® of Goldschmit AG, Essen,

(c) 400 kg fully deionized water.

The procedure is the same as in Example 1 or 2.

The basic emulsions produced in accordance with Examples 1 to 5 areprocessed as follows.

EXAMPLE 6 Production of a Mineral Fiber Insulating Mat with No SyntheticResin Bonding

With regard to production of glass fibers by a jet process, anapproximately 2% oil emulsion produced according to Examples 1 to 5 andin a quantity of 25 liters per 100 kg of glass fibers, is sprayed by aplurality of jets onto the glass fiber stream which is at a temperatureof 600° to 700° C. below the fiber producing unit (blower jet) prior toentry into the gravity shaft. After they have passed through the gravityshaft, the fibers which are now cooled to 100° to 120° C. and whichcarry an oiling agent are collected on a conveyor belt and transportedalong a 30 to 40 m cooling stage for drying purposes.

The speed of the belt below the gravity shaft is set, so that, mineralfiber mats are produced in a thickness of 30 to 120 mm and with an oilcontent of 0.2 to 0.4%.

EXAMPLE 7 Production of Mineral Fiber Insulating Panel or Mat with aSynthetic Resin Bonding

With regard to the manufacture of glass fibers by the centrifugalmethod, jet process or die drawing process, an aqueous solutioncontaining 1 to 10% by weight of solids and of the following compositionis sprayed onto the mineral fibers produced, when they are underneaththe fiber producing unit and shortly before they enter what is known asthe collecting chamber (gravity shaft):

EXAMPLE 7a

3 (1 to 10) parts by weight of a phenolformaldehyde precondensate(resolresin);

1 (0.5 to 2) parts by weight oil as a 2 (1 to 3) % emulsion, produced bythe method according to the invention as in Example 1 or 2 (oil emulsionwithout silicone).

EXAMPLE 7b

2 (1 to 10) parts by weight of a phenolformaldehyde precondensate (resolresin);

2 (0.5 to 2) parts by weight of oleo oil as a 2 (1 to 3) % emulsionproduced by the method of the invention as in Example 3 or 4 (oilemulsion with silicone).

EXAMPLE 7c

2.5 (0.4 to 5) parts by weight of a phenolformaldehyde precondensate(resol resin);

0.4 (0.2 to 0.8) parts by weight of a silicone oil in the form of a (3to 6) % aqueous emulsion produced by the method according to theinvention with 0.75% by weight carboxy methyl cellulose (Example 5)(silicone and emulsion without oil).

EXAMPLE 7d

The same as (Example 7b) but without resol resin.

The moist web of fibers formed underneath the gravity shaft is thencompressed between two perforated metal strips to a thickness of 15 to150 mm, to produce a panel or a felt while at the same time the materialis dried with hot air at 200° to 220° C. and hardened. The felt producedin this way is dried on a wire mesh to produce a rollable mat.

RESULTS

The mats and panels produced in accordance with Examples 6 and 7 weresubjected to a "submersion test" to ascertain the quantity of water theyabsorbed. The submersion test comprises the following stages.

Square test specimens measuring 200×200 mm are cut, immersed at least 30mm deep in water for 10 minutes, after which they are taken out, placedon edge for 10 minutes to allow the water to drip off and the increasein weight is ascertained (converted to liters per cubic meter). Aproduct is described as water repellant if it absorbs less water inkg/m³ than its thickness is in mm. Values up to 40 kg/m³ are acceptableregardless of thickness.

The Table represents the quantity of water absorbed (in kg/m³) withvarious products produced according to the prior art and by the methodaccording to the invention respectively.

                                      TABLE                                       __________________________________________________________________________              Mat without synthetic                                                                         Mat with synthetic resin bonding                              resin bonding   (phenol formaldehyde resol)                                   (density 90-120 kg/m.sup.3)                                                                   (density 60-85 kg/m.sup.3)                                    Production                                                                           quantity of water                                                                      Production of                                                                        Production                                                                           quantity of water                     Impregnation                                                                            of the mat                                                                           absorbed (kg/m.sup.3)                                                                  the emulsion                                                                         of the mat                                                                           absorbed (kg/m.sup.3)                 __________________________________________________________________________    With emulsifier                                                                         According to                                                                         700-850    *    According to                                                                         300-400                               containing mineral                                                                      Example 6,             Example 71                                   oil lubricant,                                                                          with *                 buth with *                                  without silicone,                                                             to the state of                                                               the art                                                                       With mineral oil                                                                          --   --       According to                                                                         According to                                                                          50-100                               emulsion, without         Examples 1                                                                           Example 7a                                   silicon, according        and 2                                               to the invention                                                              With silicon oil                                                                          --   --       According to                                                                         According to                                                                         15-30                                 emulsion, without         Example 5                                                                            Example 7c                                   mineral oil,                                                                  according to the                                                              invention                                                                     With mineral oil                                                                        (Emulsion                                                                            20-80    According to                                                                         According to                                                                          5-20                                 and silicon                                                                             according to    Examples 3                                                                           Example 7b                                   emulsion according                                                                      Example 4)      and 5                                               to the invention                                                                        According to                                                                  Example 7d                                                          __________________________________________________________________________     *Commercial oil emulsion (Praeparol ® of Stockhausen, in Krefeld).   

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed as new and desired to be secured by Letters Patent ofthe United States is:
 1. A method of impregnating artificial mineralfibers with a water soluble additive, comprising the steps of:(i)preparing an aqueous solution of a cellulose ether, (ii) dispersing awater insoluble additive selective from the group consisting of mineraloil, silicone, and mixtures thereof in said aqueous solution to producean emulsion, and (iii) spraying said artificial mineral fibers with saidemulsion, to obtain mineral fibers which contain said water insolubleadditive in an amount of 0.2 to 0.4% by weight, wherein said emulsioncomprises 0.1-2.5% by weight of said cellulose ether relative to saidwater insoluble additive.
 2. The method of claim 1, wherein saidcellulose ether is selected from the group consisting of hydroxyethylcellulose, methyl hydroxyethyl cellulose, sodium carboxymethyl celluloseand mixtures thereof.
 3. The method of claim 1, wherein said emulsioncomprises 0.2-1% by weight of said cellulose ether relative to saidwater insoluble additive.